iTunes store isn't working.

-I use IOS7 on the iPhone 4-

My itunes store appears to be broken. For the past few days, everytime I try to enter the store from my phone, after around 3-5 seconds the screen flashes black and I am sent back to the homepage. I've tried restarting my phone, dełeting some apps and making storage and also turning my phone off and back on again. My sister uses ios7 on her iPhone 5 and her iTunes store is working perfectly fine. I can listen to my music that I bought months ago but when from "Music" (the inbuilt thing) I try to access the store, the screen turns white and says it is unable to connect to the store. However, my app store is working fine and I have been able to purchase some apps from there recently, although I can't say I use my itunes store much so it could have broken months ago for all I know.

Any suggestions would be great :)

I just remembered that since the first update to ios7, I haven't updated my operating system (to 7.1 etc). Could that be the problem?